A collection of commands

commands.sh

# Virtualbox: Mount the shared folder 
sudo mount -t vboxsf temp Shared

# process listening on a port (e.g. 5000)
lsof -i :5000                                  # find the process
lsof -i :80                                    # find the program running on a port
kill -9 PID                                    # kill process
sudo netstat -lpn |grep :5000
netstat -tan | grep ':80 ' | awk '{print $6}' | sort | uniq -c # view list of connections and their states
ss -rota | less                                # list all connections and timers

find / -name filename                          # search for a file
find . -type f | wc -l                         # count files in current and subsequent folders
find . -name "*.gz" | xargs -J {}  mv {} /tmp/ # moving .gz files into /tmp/
grep -R "test" /var/x/                         # search a string in folder recursively
grep -rnw '/path/to/somewhere/' -e "pattern"   # search a string in folder and gives line number in file
cmd >>file.txt 2>&1                            # forward stdout and stderr to a file
sudo passwd root                               # reset root password
sudo -H -u otheruser bash -c 'echo "I am $USER, with uid $UID"' # run a command with another user
for f in *.txt; do echo "Processing $f"; done  # loop over files and do some work
jar tf my-fat-jar-file.jar | grep filename     # print the content of a jar and look for a given file

# create certificate for https server
openssl genrsa -out server.key 2048
openssl req -new -x509 -key server.key -out server.pem -days 3650

# write something to a file
cat << EOF > file
cd "$HOME"
echo "$PWD" # echo the current path
EOF

< file tee file-{001..100}                     # repeat a file a hundread time
cat file-* > file                              # copy the content of multiple files into one
echo "hello world" >> my_file.txt              # append a line of text to a file by using the >> operator
sudo sh -c 'echo "hello world" >> my_file.txt' # append a line of text to a file as root
split -l line_count file_name                  # split a file into multiple pieces by line_count lines

ln -s /path/to/file /path/to/symlink           # create a symbolic link

# create executable jar
echo Main-Class: Craps > manifest.txt
jar cfm filename.jar manifest.txt Classname.class ...

# windows save some space
powercfg -h off

# hadoop
hdfs dfsadmin -report
yarn logs --applicationId <application> --containerId <container> -nodeAddress hadoop-server-2:49030
yarn application -kill <application>

# Administration commands:
sudo apt-get install htop # cpu/mem usage
egrep --color 'Mem|Cache|Swap' /proc/meminfo # available mem

#Checking for disk space on HDFS: 
hdfs dfs -du -h /
hadoop dfsadmin -report

#Making the NodeManager leaves its safe mode: 
hdfs dfsadmin -safemode leave

# vagrant
vagrant init
vagrant box add hashicorp/precise32 #Vagrantfile config.vm.box = "hashicorp/precise32"
vagrant up --provider virtualbox
# when vitual box guest os is missing
vagrant plugin install vagrant-vbguest
vagrant vbguest